Stanhopea platyceras bud drop

[AmandaTom]

Twice now my Stanhopea platyceras has spiked and twice I have lost the bud well before opening. The stem just dries up. In the first case, I am not sure what happened but the second time I changed out my lights with stronger bulbs. Would this cause the buds to drop? Are Stans really sensitive to changes in light?
Thanks for any help.
Amanda

[Frdemetr]

Hi Amanda,

as a group, Stans are usually easy to cultivate and to bloom; I guess Stan platyceras is especially difficult, mine is hard to grow, if yours are in spike (even if the buds dropped-out) I think it's a happy plant! Sometimes, intended to improve, we disturb our plants; if the plant is doing well, don't mess with it!

[Manfred Busche]

Hello Amanda.

I have some 100 Stanhopea plants, perhaps I can contribute to solve your problem (?).

Some questions first, however - your plant has ...
-- (a) how many bulbs ?
-- (b) one 'Big-Fat' bulb ?
-- (c) bulbs very much shriveled ?
-- (d) how many leaves ?
-- (e) leaf-length 20" or more ?
-- (f) been regularly fertilised, except during dormancy ?
-- (g) been fertilised incl. during dormancy ?

Sorry to have to ask so many questions ...
Regards, MANFRED.

[AmandaTom]

a) 7 bulbs
b) various sized bulbs--none significantly bigger than any others
c) none shriveled
d) 5 leaves
e) all leaves 20+"
f) fertilized every 3 weeks or so
g) sad to say, I don't know when the dormancy period is so must have fertilized then too
h) the plant is indoors under lamps--two 2000 fc tubes about 14" above plant.
Humidity 55-75%
Temp 65-80 F

[Manfred Busche]

Good for you: you have a potentially strong plant.

Bad for the plant :: you have fertilised her (perhaps for years?) when she hates fertilisation : during her
Period of Dormancy.

I suggest that you consider to act as follows.

(a) Change the plant's compost now, and in the future change compost every two (2) years or earlier.
(b) Water moderately now but do not fertilise.
(c) Water more when a new leaf shoot has appeared, but still do not fertilise.

(d) When this new leaf shoot has grown to a length of 1 inch : FERTILISE (!) with 3o-10-10.
(e) Fertilise the plant (1000 ppm per week) until the new leaf shoot is as tall as the other leaves and
.....has developed a bulb as big as the others, or
.....a bulb even bigger: a 'Big-Fat' Bulb which later will produce a flower.

(f) When the new bulb has grown as big as the others or even 'Big-Fat', DORMANCY begins; do not miss out.

.....The plant's dormancy is nothing to be taken from the calendar but is determined by the plant herself (!).
.....NO FERTILISATION during dormancy, but occasional watering is a requirement indeed.

(g) After Dormancy (1-4 months), the plant will spike if she had produced a 'Big-Fat' Bulb or, if not,
.....will grow a new leaf shoot and the cycle, see (c) above, begins anew.
.....If the plant spikes: FERTILISE with 10-50-10.

(h) Organic fertiliser :: NO (!) - much better something like PETERS.

(i) Light required: equivalent to light from a clear sky falling through a tree (dappled light).
.....Less light = failure (!) - measure the light your plant gets and adjust.

(k) Observe your plants passionately at all times.

(l) Spread this news , to better the fate of Stanhopea plants in cultivation ...

(m) To see healthy Stanhopea plants, cultivated as described above, log on to
.....BERGGARTEN ORCHIDS - Home.

[AmandaTom]

Thank you! I have followed your advice and she is in spike again so hopefully this time I will get a flower!

[Manfred Busche]

Now use a Fertiliser rich with Phosphoric Acid : N-P-H = 10-50-10 (approx.)
Amount / quantity : 1000 ppm per week, given every 3 days = approx. 400 ppm each time.

[AmandaTom]

I better get some different fertilizer. I just read the label and it's 20-10-20, the opposite of what I need.

[Manfred Busche]

Yes, better do...
To support a new spike, Stanhopea plants need 10-50-10 (approx) of instantly available minerals;
best given every 3 days in amounts of 400 ppm (parts per million) each time.
To support a new leaf : 30-10-10 (approx), same amount.

Organic Fertilizer : BAD because, obviously, the stuff requires to be broken down first by bacteria and
fungi (takes a year), before the then available minerals can be utilised by your plant.
Hence no instant availability of minerals - but lots of chum which draws lots of bugs...

Light: this new spike of your plant will fail again should you fertilise well indeed but fail to give
the plant the light she requires - I suggest that you observe (i) above.
My Stanhopeas get full sun (dappled / mottled with shade) until 10.30 a.m.

[AmandaTom]

My plant is under two T5 lights, one red and one blue. The tops of the leaves are about 2" below the light, and the base of the plant about 18" away. The lights are on from 7am until 11pm. The basket is hanging so as to get air movement and it is planted in spag.

I bought new fertilizer today. The lady at the store wanted to sell me something that was "for orchids" but remembering your advice I noticed it was not the right mix. The only one I could find is 5-50-17--not quite right but close and the phosphorus is the right strength.

Am I on the right track this time (if I vote for Obama)?